Embodiments generally relate to a system and method for determining causes of irregularities, such as noise, within an implantable medical device (IMD), and more particularly to a system and method for determining causes of irregularities within an IMD through the use of a position detector, such as an accelerometer.
Numerous medical devices exist today, including but not limited to electrocardiographs (ECGs), electroencephalographs (EEGs), squid magnetometers, implantable pacemakers, implantable cardioverter-defibrillators (ICDs), implantable cardiac resynchronization devices (CRTs), implantable cardiac monitors, neurostimulators, electrophysiology (EP) mapping and radio frequency (RF) ablation systems, and the like (hereafter generally “implantable medical devices” or IMDs). IMDs commonly employ one or more leads with electrodes that either receive or deliver voltage, current or other electromagnetic pulses from or to an organ or tissue for diagnostic or therapeutic purposes.
Many IMDs, such as pacemakers and ICDs, are susceptible to noise generated by electromagnetic interference (EMI), myopotential oversensing (for example, signals generated by movement of a patient's arms and chest muscles), and/or intermittent lead fractures. Based on the generated noise, an IMD may deliver an inappropriate therapy, for example.
Typically, a physician reviews the signals from the IMD. For example, a physician may view an intracardiac electrogram (IEGM) or electrocardiogram (ECG) saved within an IMD. The physician may see noise or other such irregularities in the IEGM or ECG, but may not be able to discern the cause of the irregularities. In an effort to determine the nature of the irregularities, the physician may ask the patient about the nature of what he/she was doing at the time of a particular irregularity. However, the patient may not be able to recall what he/she was doing at the time of the irregularity. The physician may then ask the patient to engage in a series of physical movements and maneuvers, such as moving his/her arms, in an effort to recreate the irregularity within the IEGM or ECG. However, the movements and maneuvers may not generate a response signal in the IEGM or ECG that matches the original irregularity. Consequently, the physician may conclude that the noise or irregularity shown in the IEGM or ECG was merely caused by EMI. However, the noise or irregularity may actually have been caused by myopotential oversensing or a lead fracture within the IMD. As such, the physician may miss an opportunity to adapt sensing parameters of the IMD, or recommend a new lead.